A Study to Evaluate Efficacy, Safety, Pharmacokinetics, and Pharmacodynamics of Multiple Doses of Natalizumab (BG00002) Administered Subcutaneously to Japanese Participants With Relapsing-Remitting Multiple Sclerosis

Treatment tested

• Natalizumab

  Integrin alpha-4/beta-1 inhibitor|Integrin alpha-4/beta-7 inhibitor

Other measures (20)

Key Inclusion Criteria: * Must have had a diagnosis of RRMS, as defined by the revised 2017 McDonald's criteria. All other possible neurologic diagnoses must have been reasonably excluded by means of laboratory and/or imaging studies, in the opinion of the investigator. * Must have had an EDSS score between 0.0 and 5.5, inclusive. * Must have had screening MRI or documentation of an MRI within the participant's medical record within 12 months of the screening visit that revealed 3 or more T2 hyperintense lesions consistent with MS. * Was born in Japan, and biological parents and grandparents were of Japanese origin. Key Exclusion Criteria: * Evidence of current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection within 14 days prior to Screening, between screening and baseline visit, or at baseline visit, including but not limited to a fever (temperature > 37.5 degrees Celsius [°C]), new and persistent cough, breathlessness, or loss of taste and/or smell. * Have close contact within 14 days prior to Day 1 with a SARS-CoV-2 positive individual. * Diagnosis of primary progressive MS or secondary progressive MS. * An MS exacerbation (relapse) within 30 days prior to enrolment or, in the opinion of the investigator, the participant not having stabilized from a previous relapse prior to enrolment (Day 1). * The participant is unable to have a brain MRI scan (e.g., a participant with a metal clip to repair a cerebral aneurysm). * Previous exposure to natalizumab. Note: Other protocol specified Inclusion/Exclusion criteria may apply.

The primary objective of this study is to evaluate the efficacy of natalizumab 300 milligrams (mg) subcutaneous (SC) every 4 weeks (Q4W) administrations up to 24 weeks in Japanese participants with relapsing-remitting multiple sclerosis (RRMS). The secondary objectives of the study are to evaluate other clinical and magnetic resonance imaging (MRI) measures of efficacy of natalizumab 300 mg SC Q4W administrations in Japanese participants with RRMS, to evaluate the safety, tolerability, and immunogenicity of natalizumab 300 mg SC Q4W administrations up to 48 weeks in Japanese participants with RRMS, to evaluate the pharmacokinetics (PK) and pharmacodynamics (PD) of natalizumab 300 mg SC Q4W administrations up to 24 weeks and for an additional 24 weeks in Japanese participants with RRMS.